Coating formulation and application of organic passivation layer onto iron-based rare earth powders

ABSTRACT

The present disclosure relates to coating formulations for neodymium-iron-boron type magnetic powders manufactured from rapid solidification processes for the purpose, inter alia, of corrosion and oxidation resistance when exposed to aggressive environments. The coating formulation preferably contains an epoxy binder, curing agent, an accelerating agent, and a lubricant. By incorporating coupling agents and optionally, other specialty additives with the magnetic powder and the organic epoxy components, additional oxidation and corrosion prevention, enhanced adhesion and dispersion between the filler and matrix phases can be achieved. This disclosure relates to all such rare earth-transition metal-boron (RE-TM-B) powders produced by rapid solidification and encompasses both the bonded magnet products that include combinations of the materials mentioned and the application processes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 60/524,633, filed Nov. 25, 2003, the disclosureof which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to coating formulations for rareearth-transition metal-boron (RE-TM-B) magnet materials, such asneodymium-iron-boron type magnetic powders manufactured from rapidsolidification processes for, among other things, the purpose ofcorrosion and/or oxidation resistance when exposed to aggressiveenvironments or for passivation. The present invention also relates tomethods of applying coating formulations to rare earth-transitionmetal-boron (RE-TM-B) magnet powders.

BACKGROUND OF THE INVENTION

Isotropic polymer bonded rare earth permanent magnets have been used invarious advanced motors and electronic devices. With the miniaturizationof motors and electronic devices, it is necessary to reduce the size ofmagnets used. To enable effective miniaturization and efficient energyor signal output, it is essential for these applications to demandmagnets of high flux densities. Factors determining the flux density ofisotropic polymer bonded magnets can be divided into two parts: the typeof magnet materials used and the volume fraction of the magnet materialsin these polymer bonded magnets.

The criteria for selecting the type of magnetic materials are stronglyinfluenced by the operation conditions demanded by the givenapplications. The polymer binder used for making polymer bonded magnetsmust be able to provide sufficient mechanical strength to hold magnetpowder together and maintain the designed shape specification up to theintended operation temperature and to sustain that operation temperaturewithout softening, deforming or breaking. The magnetic materials mustprovide sufficient flux to sustain the desired properties at theoperation temperature without substantial loss of magnetization. Theflux aging loss of a magnet material provides an indication of themagnet material's stability to heat and protection from corrosive andoxidative environments, which can affect the magnetic materials' abilityto retain magnetic flux over time durations at certain temperatures. Theflux aging loss of a bonded magnet ultimately determines the magnet'sutility in various applications, and should be minimized if the bondedmagnet is to be used for high temperature applications. The oxidative orcorrosive degradation of the constituent materials and change in overallmagnetic properties should be minimized to enhance the utility of thebonded magnets.

The combination and amounts of the organic and magnetic materials shouldallow the desired properties previously discussed to be optimized andattained. The amount of magnet powder in the polymer-bonded magnets,typically stated as a mass or volume fraction, is determined by thepolymer binder type, molecular weight of the polymer binder, and themethodology applied in order to combine said materials effectively.Depending on the molding method, various polymers are available formaking isotropic bonded magnets. Compression molding, injection molding,extrusion and calendering are well-known means for producingpolymer-bonded magnets in commercial quantities.

Compression-molded or compacted magnets allow magnets to reach high,desirable volume fraction (greater than 83%) required to achieve strongmagnetic properties. Typically, thermosetting polymers, such as,epoxies, phenolics, and other crosslinkable resins with their respectivecuring agents are used with the ideology of producing magnets that willless affected by heat or chemical attack than the non-coated powders.These materials are initially low molecular weight substances that canbe easily applied as coatings for the magnetic powders. The componentscan be molded and cured to produce magnets that are resistant to hightemperatures (typically, not much greater than 250° C.) and chemicalsolvents. The extent of crosslinking or the crosslink density of thethermosetting binder governs the coating's overall resistance tooxidation and corrosion as well as the mechanical strength of the finalmagnet.

At high loadings of solid filler the oxidation potential of the magneticpowders increases and becomes deleterious to the magnetic propertiesbecause of the low degree of organic protection, where the industry term“loading” refers to the proportion of magnet powder in the final magnetproduct. Chemical additives are introduced into the bonded magnet systemin order to alleviate oxidative effects on the metallic fillerparticles. U.S. Pat. No. 5,888,416 to Ikuma et al. discloses the use ofvarious chelating agents and antioxidants in the rare-earth bondedmagnets of polyphenylene sulfide (PPS), nylon 12 (polyamide), andpolyethernitrile (liquid crystal polymer) thermoplastic binders for usein extruded magnet compositions. U.S. Pat. No. 5,395,695 to Shain et al.discloses incorporating successive layers of an antioxidant, an epoxynovolac resin, and polystyrene onto the magnet material for improvementsin oxidation resistance, with an emphasis on the sequential layering ofthe components. Xiao et al. and Guschl et al. describe the benefits ofincorporating an aminosilane coupling agent onto the powders within apolyphenylene sulfide binder. See J. Xiao and J. U. Otaigbe, “HighPerformance, Lightweight Thermoplatic/Rare Earth Alloy Magnets,” Mat.Res. So. Symp. Proc., 577:75-80 (1999); P. C. Guschl, H. S. Kim, and J.U. Otaigbe, “Effects of a Nd—Fe—B Magnetic Filler on the Crystallizationof Poly(phenylene sulfide),” J. Appl. Poly. Sci., 83:1091-1102 (2002).However, the results disclosed in these references were based solely onmagnets with powder loadings on the order of about 80%, which is lowerthan those achievable in compression-molding magnets (on the order ofabout 90% or more). U.S. Pat. No. 4,876,305 to Mazany (“Mazany”)describes the application of a combination of aminosilanes andepoxysilane coupling agents with epoxy resins for oxidation resistance,comparing oxidation rates to treated and non-treated samples. Theconcentrations of magnetic material in the magnets disclosed in Mazanywere fairly low, the magnetic properties of the resultant magnets, e.g.,the flux aging loss, are not considered relevant.

U.S. Pat. No. 5,087,302 to Lin et al. discloses a process where anorganotitanate is added to coarse Nd—Fe—B powders during a milling stepto produce sintered magnets with improved magnetic remnance, coercivityand oxidation resistance. However, since the milled magnetpowder-organotitanate mixture is subjected to a high-temperaturedegassing technique in an inert atmosphere in order to manufacture thesintered NdFeB magnets, the organotitanate is removed or “degassed” fromthe metallic powders.

Recently published coupling agents that have been utilized in bondedmagnet systems are the organotitanates and organozirconates. SeveralJapanese patents describe the use of these agents and NdFeB powders withmainly nylon 12 resin, epoxy resins, PPS resin, and other suchthermoplastic or thermosetting binders. See, e.g., JP-03165504 to T.Hitoshi et al.; JP-03222303 to M. Yoshihiko; JP-04011701 to M.Yoshihiko; and JP-04257203 to T. Hitoshi et al. These disclosures aredirected to applications to injection-molding and extrusion-producedbonded magnets, because the specification of the material types andcompositions disclosed therein fall well below the magnetic powderloadings disclosed in the present invention. Chen et al. disclose that adiaminoethylene-based titanate incorporated into a NdFeB-epoxy-bondedmagnet system improved the bonding of the components and overallspecific density of the magnet. See Q. Chen, J. Asuncion, J. Landi, andB. M. Ma, “The Effect of the Coupling Agent on the Packing Density andCorrosion Behavior of NdFeB and SmCo Bonded Magnets,” J. Appl. Phys.,85:8:5684-5686 (1999). However, no mention is made of the effects of thetitanate on the flux aging loss of the magnet material or of the methodin which the titanate was incorporated into the system. The presentinvention provides a more effective technique for protecting rareearth-transition metal-boron magnetic materials through a performingliquid coating procedure on the rare earth-transition metal-boron magnetpowders. The present invention is applicable, for example, tocompression-molding magnets.

SUMMARY OF THE INVENTION

In a first embodiment, the present invention provides a rapidlysolidified rare earth-transition metal-boron magnet material, comprisinga rare earth-transition metal-boron magnet powder coated with a coatingcomprising, in an amount by weight of the magnet powder, of about 0.1weight percent to about 1 weight percent of an organotitanate ororganozirconate coupling agent, about 0.18 weight percent to about 4.46weight percent of an epoxy resin, about 0.01 weight percent to about0.27 weight percent of an amine-based hardener, about 0.004 weightpercent to about 0.09 weight percent of an accelerator, and about 0.003weight percent to about 0.27 weight percent of a lubricant. The generalform of the coupling agent is:(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n)where R is a neopentyl(diallyl), dioctyl, or (2,2-diallyloxymethyl)butylgroup, Ti or Zr has a coordination number of 4, R′ is a phosphito,pyrophosphato or cyclic pyrophosphato segment, and Y is a dioctyl orditridecyl end group, with 1≦n≦4. In first aspect according to the firstembodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, where the coatingcomprises about 0.1 weight percent to about 1 weight percent of theorganotitanate or organozirconate coupling agent, about 0.43 weightpercent to about 3 weight percent of the epoxy resin, about 0.025 weightpercent to about 0.18 weight percent of the amine-based hardener, about0.009 weight percent to about 0.06 weight percent of the accelerator,and about 0.009 weight percent to about 0.19 weight percent of thelubricant. In specific embodiment of the invention, the coatingformulations of the first embodiment of the invention consistsessentially of the recited components in the recited percentage ranges.

In a second embodiment, the present invention provides a rapidlysolidified rare earth-transition metal-boron magnet material, comprisinga rare earth-transition metal-boron magnet powder coated with a coatingcomprising, in an amount by weight of the magnet powder, of about 0.225weight percent to about 4.25 weight percent of epichlorohydrin/cresolnovolac epoxy resin, about 0.01 weight percent to about 0.26 weightpercent of dicyandiamide hardener, about 0.005 weight percent to about0.085 weight percent of an aromatic, tertiary amine accelerator, about0.004 weight percent to about 0.27 weight percent of zinc stearatelubricant, and about 0.35 weight percent to about 0.75 weight percent ofan organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃where R is a neopentyl(diallyl), Ti has a coordination number of 4, R′is a pyrophosphato segment, and Y is a dioctyl end group. In a firstaspect of the second embodiment, the invention provides a rapidlysolidified rare earth-transition metal-boron magnet material, where thecoating comprises about 0.68 weight percent to about 2.76 weight percentof epichlorohydrin/cresol novolac epoxy resin, about 0.04 weight percentto about 0.17 weight percent of dicyandiamide hardener, about 0.01weight percent to about 0.055 weight percent of the aromatic, tertiaryamine accelerator, about 0.01 weight percent to about 0.175 weightpercent of the zinc stearate lubricant. In specific embodiment of theinvention, the coating formulations of the second embodiment of theinvention consists essentially of the recited components in the recitedpercentage ranges.

In a third embodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, comprising a rareearth-transition metal-boron magnet powder; and an organotitanate ororganozirconate coupling agent of the general form(RO—)_(n)(Ti or Zr)(—OR′Y_(4-n)where R is a neopentyl(diallyl), dioctyl, or (2,2-diallyoxymethyl)butylgroup, Ti or Zr has a coordination number of 4, R′ is a phosphito,pyrophosphato or cyclic pyrophosphato segment, and Y is a dioctyl orditridecyl end group, with 1≦n≦4; where the coupling agent is present inan amount by weight of the magnet powder of about 0.1 weight percent toabout 1 weight percent. In a first aspect of the third embodiment, theinvention provides a rapidly solidified rare earth-transitionmetal-boron magnet material, where the organotitanate or organozirconatecoupling agent is of the form:(RO—)(Ti or Zr)(—OR′Y)₃where R is a neopentyl(diallyl) group, Ti has a coordination number of4, R′ is a pyrophosphato segment, and Y is a dioctyl end group, wherethe coupling agent is present in an amount by weight of the magnetpowder of about 0.35 weight percent to about 0.75 weight percent. Inspecific embodiment of the invention, the coating formulations of thethird embodiment of the invention consists essentially of the recitedcomponents in the recited percentage ranges.

In a fourth embodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, comprising a rareearth-transition metal-boron magnet powder comprising a pre-coating ofan organotitanate or organozirconate coupling agent of the general form:(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n)

where R is a neopentyl(diallyl), dioctyl, or (2,2-diallyloxymethyl)butylgroup, Ti or Zr has a coordination number of 4, R′ is a phosphito,pyrophosphato or cyclic pyrophosphato segment, and Y is a dioctyl orditridecyl end group, with 1≦n≦4, present in an amount by weight of themagnet powder of about 0.1 weight percent to about 1 weight percent; anda further coating comprising, in an amount by total weight of the finalmixture, of about 0.18 weight percent to about 4.46 weight percent of anepoxy resin, about 0.01 weight percent to about 0.27 weight percent ofan amine-based hardener, about 0.004 weight percent to about 0.09 weightpercent of an accelerator, and about 0.003 weight percent to about 0.27weight percent of a lubricant. In a first aspect of the fourthembodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, where the further coatingcomprises about 0.43 weight percent to about 3 weight percent of epoxyresin, about 0.025 weight percent to about 0.18 weight percent ofamine-based hardener, about 0.009 weight percent to about 0.06 weightpercent of accelerator, and about 0.009 weight percent to about 0.19weight percent of lubricant. In specific embodiment of the invention,the coating formulations of the fourth embodiment of the inventionconsists essentially of the recited components in the recited percentageranges.

In a fifth embodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, comprising a rareearth-transition metal-boron magnet powder comprising a pre-coating ofan organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃

where R is a neopentyl(diallyl) group, Ti has a coordination number of4, R′ is a pyrophosphato segment, and Y is a dioctyl end group, presentin an amount by weight of the magnet powder of about 0.35 weight percentto about 0.75 weight percent; and a further coating comprising, in anamount by weight of the final mixture, of about 0.225 weight percent toabout 4.25 weight percent of epichlorohydrin/cresol novolac epoxy resin,about 0.01 weight percent to about 0.26 weight percent of dicyandiamidehardener, about 0.005 weight percent to about 0.085 weight percent of anaromatic, tertiary amine accelerator, and about 0.004 weight percent toabout 0.27 weight percent of zinc stearate lubricant. In a first aspectof the fifth embodiment of the invention, the invention provides arapidly solidified rare earth-transition metal-boron magnet materialcomprising the pre-coating of the organotitanate coupling agent at aconcentration range of 0.35-0.75% by weight of the rare earth-transitionmetal-boron powder; and the further coating of, by total weight,0.680%-2.76% epichlorohydrin/cresol novolac epoxy resin, 0.040-0.170%dicyandiamide hardener, 0.010-0.055% of the aromatic, tertiary amineaccelerator, 0.010-0.175% zinc stearate lubricant. In specificembodiment of the invention, the coating formulations of the fifthembodiment of the invention consists essentially of the recitedcomponents in the recited percentage ranges.

In a sixth embodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, comprising a rareearth-transition metal-boron magnet powder coated with a coatingcomprising, in an amount by weight of the magnet powder, of about 0.65weight percent to about 2.5 weight percent of an epoxy resin, about0.035 weight percent to about 0.15 weight percent of an amine-basedhardener, about 0.01 weight percent to about 0.05 weight percent of anaccelerator, about 0.04 weight percent to about 0.16 weight percent of alubricant, about 0.001 weight percent to about 0.3 weight percent of anorganoclay, and about 0.35 weight percent to about 0.75 weight percentof an organotitanate or organozirconate coupling agent of the generalform(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n)where R is a neopentyl(diallyl), dioctyl, or (2,2-diallyoxymethyl)butylgroup, Ti or Zr has a coordination number of 4, R′ is a phosphito,pyrophosphato or cyclic pyrophosphato segment, and Y is a dioctyl orditridecyl end group, with 1≦n≦4. In a first aspect of the fifthembodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, wherein the coupling agentis an organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃

where R is a neopentyl(diallyl), Ti has a coordination number of 4, R′is a pyrophosphato segment, and Y is a dioctyl end group. In a firstaspect of the fifth embodiment, the epoxy resin isepichlorohydrin/cresol novolac epoxy resin, the amine-based hardener isdicyandiamide hardener, the accelerator is an aromatic, tertiary amineaccelerator, the lubricant is zinc stearate, and the organoclaycomprises bis (hydroxyethyl) methyl tallow alkyl ammonium salts withbentonite. In a second aspect of the fifth embodiment, the coating ofthe rapidly solidified rare earth-transition metal-boron magnet materialcomprises about 0.001 weight percent to about 0.3 weight percent of anorganoclay comprising bis (hydroxyethyl) methyl tallow alkyl ammoniumsalts with bentonite; and about 0.35 weight percent to about 0.75 weightpercent of an organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃

where R is a neopentyl(diallyl), Ti has a coordination number of 4, R′is a pyrophosphato segment, and Y is a dioctyl end group. In specificembodiment of the invention, the coating formulations of the sixthembodiment of the invention consists essentially of the recitedcomponents in the recited percentage ranges.

In a seventh embodiment, the invention provides a rapidly solidifiedrare earth-transition metal-boron magnet material, comprising a rareearth-transition metal-boron magnet powder; which has been pre-coatedwith a POSS additive in an amount by weight of the magnet powder ofabout 0.1 weight percent to about 5 weight percent; after which afurther coating is applied, which comprises, in an amount my totalweight of the mixture, of about 0.54 weight percent to about 2.75 weightpercent of an epoxy resin, about 0.03 weight percent to about 0.17weight percent of an amine-based hardener, about 0.01 weight percent toabout 0.06 weight percent of an accelerator, about 0.035 to about 0.175weight percent of a lubricant, about 0.35 weight percent to about 0.75weight percent of an organotitanate or organozirconate coupling agent ofthe general form(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n)

where R is a neopentyl(diallyl), dioctyl, or (2,2-diallyloxymethyl)butylgroup, Ti or Zr has a coordination number of 4 or 5, R′ is a phosphito,pyrophosphato or cyclic pyrophosphato segment, and Y is a dioctyl orditridecyl end group, with 1≦n≦4, about 0.003 weight percent to about0.055 weight percent of an organoclay, and about 0.003 weight percent toabout 0.015 weight percent of an antioxidant agent. In a first aspect ofthe seventh embodiment, the invention provides a rapidly solidified rareearth-transition metal-boron magnet material, where the coupling agentis an organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃

where R is a neopentyl(diallyl), Ti has a coordination number of 4, R′is a pyrophosphato segment, and Y is a dioctyl end group. In specificembodiment of the invention, the coating formulations of the seventhembodiment of the invention consists essentially of the recitedcomponents in the recited percentage ranges.

In a second aspect of the seventh embodiment, the POSS additive istrisilanolphenyl or epoxycyclohexyl POSS. In a third aspect of theseventh embodiment, the antioxidant agent is a butylated reactionproduct of p-cresol and dicyclopentadiene antioxidant. In a fourthaspect of the seventh embodiment, the epoxy resin isepichlorohydrin/cresol novolac epoxy resin, the amine-based hardener isdicyandiamide hardener, the accelerator is an aromatic, tertiary amineaccelerator, the lubricant is zinc stearate lubricant; and the organoclay additive is bis (hydroxyethyl) methyl tallow alkyl ammonium saltswith bentonite.

In a fifth aspect of the seventh embodiment, the pre-coating is atrisilanolphenyl or epoxycyclohexyl POSS in an amount of about 0.1weight percent to about 1 weight percent, by weight of the magnetpowder; and the further coating comprises, by total weight of themixture, of about 0.54 weight percent to about 2.75 weight percent ofepichlorohydrin/cresol novolac epoxy resin, about 0.03 weight percent toabout 0.17 weight percent of dicyandiamide hardener, about 0.01 weightpercent to about 0.06 weight percent of an aromatic, tertiary amineaccelerator, about 0.035 weight percent to about 0.175 weight percent ofzinc stearate lubricant,

about 0.35 weight percent to about 0.75 weight percent of anorganotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃where R is a neopentyl(diallyl), Ti has a coordination number of 4, R′is a pyrophosphato segment, and Y is a dioctyl end group, about 0.003weight percent to about 0.07 weight percent of an organoclay comprisingbis (hydroxyethyl) methyl tallow alkyl ammonium salts with bentonite,and about 0.003 weight percent to about 0.015 weight percent of abutylated reaction product of p-cresol and dicyclopentadieneantioxidant.

The present invention also provides a process of liquid-coating arapidly solidified rare earth-transition metal-boron magnet material,comprising the steps of providing a solution comprising a solvent, anorganotitanate or organozirconate coupling agent, an epoxy resin,hardener, an accelerator, and a lubricant, wherein said homogeneoussolution is a homogeneous 8-25% solution; combining a rareearth-transition metal-boron magnet material with the homogeneoussolution to form a slurry mixture; stirring the slurry mixtureperiodically; and maintaining said slurry mixture at a temperaturebetween 40-60° C., such that said solvent evaporates. In differentembodiments, the solvent is acetone or tetrahydrofuran. Various othercomponents can be introduced into to the homogeneous 8-25% solution,including an organoclay, an antioxidant agent, an organotitanate ororganozirconate coupling agent, or both types f coupling agents. In aspecific embodiment, the mixture is maintained at a temperature between50-60° C. In an alternate embodiment, the rare earth-transitionmetal-boron material is pre-treated by dissolving an organotitanate oran organozirconate coupling agent in acetone to form a 50% solution;adding the rare earth-transition metal-boron powder into the solution;and evaporating the acetone solvent to produce the pre-treated rareearth-transition metal-boron powder. In a specific embodiment, thesolvent is tetrahydrofuran, and the process further comprisespre-treating the rare earth-transition metal-boron powder by dissolvinga POSS additive in tetrahydrofuran to form a 50% solution; adding therare earth-transition metal-boron powder into the solution; andevaporating the tetrahydrofuran to produce said pre-treated rareearth-transition metal-boron powder. In specific embodiment of theprocess of liquid-coating a rapidly solidified rare earth-transitionmetal-boron magnet material, the coating consists essentially of therecited components in the recited percentage ranges.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Flux aging loss at 180° C. after 100 hours of cured PC-2 magnetswith a without a coupling agent.

FIG. 2: A comparison of the flux aging loss for cured PC-2 magnets ofeach embodiment aged at 180° C. for 100 hours.

FIG. 3: A comparison of the flux aging loss for cured PC-2 magnets offirst and fourth embodiments aged at 180° C. for 100 hours.

FIG. 4: A comparison of the flux aging loss for cured PC-2 magnets offirst, third and fifth embodiments aged at 200° C. for 100 hours.

FIG. 5. Flux aging loss of MQP 14-12™ bonded magnets with and withoutLICA 38 coupling agent after 100 hours at 180, 200, and 225° C.

FIG. 6. Flux aging loss of non-silanated and silanated MQP-B™liquid-coated magnets at 180° C. after 78 hours.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides coating formulations for rapidlysolidified rare earth-transition metal-boron (RE-TM-B)-type bondedmagnetic materials, and methods of applying such formulations to themagnet materials, with emphasis on their protection against oxidation.Specifically, the flux aging loss of any bonded magnet must be minimizedin order for high temperature applications to be considered. While notbeing bound by any specific theory, it is believed that theincorporation of organic materials, such as polymers with the inorganicmetallic powders provides a means to passivate and prevent oxidativetendencies by reducing the reactivity of the filler surfaces or bydecreasing the permeation of energetic oxygen molecules to the fillersurfaces. Additionally, the coated powders allow a higher degree offlexibility and moldability for producing bonded magnets.

The coating formulations and processes of the present invention providefor bonded magnets with higher powder loadings, i.e., higher proportionsof magnet materials contained in the final magnet, than achievable fromother methods. Prior art references disclose magnets with powderloadings lower than those achievable in the present invention, which ison the order of about 95% to about 99% or more by weight of the magnet.For example, magnets made using, e.g., polyphenylene sulfide (PPS) ornylon 12 (polyamide), such as injection-molded bonded magnets, usuallycontain only about 85% to about 93% by weight or less of magnet powder,corresponding to about 50-70% by volume.

The prior art for bonded magnets, using polymeric binders, has focusedon dry blending techniques. These methods physically mix organicpowders, such as thermosetting resins, with the magnetic powders in theabsence of solvents. Compaction and/or compression molding are used inorder to form the solid magnets by initially fusing the organic powderbetween the inorganic particles. These resultant magnets contain weaklybound particulates with nonuniformities and, as a result, a degree ofporosity, which can be detrimental in terms of oxidation, flux agingloss, and overall magnetic and physical properties.

Liquid coating techniques assuage these problems associated with dryblending by providing a uniform organic layer on the powders. Thisresulting uniformity provides more effective oxidation protectionfollowing the cure reaction of the thermosetting binder. Both liquid andsolid, dissolvable resins and other additives are permissible for theapplication process.

The polymer-coated powders of the present invention have improvedthermal stability in comparison to the magnetic powders alone. Further,more effective protection can be achieved through the addition ofparticular specialty chemical additives. While certain antioxidants canbe effective for protective purposes to some extent, the presence of theantioxidants only mildly deters oxygen molecules from reaching thefiller surfaces. Because the antioxidant molecules are freely suspendedwithin the binder matrix and deposited on the filler particles (such asin a physisorption process), they have limited ability in oxidationprotection. In other words, little to no interaction betweenthermoplastic binders, filler particles and these additives may occur(such as in a chemisorption). Possible side reactions of binders withreactive epoxide functional groups of epoxy resins may happen if theantioxidant agent contains active amine groups. However, althoughcomplete protection from oxidation may not be possible for systems thatcontain solely antioxidants, their use does aid in oxidation prevention.Accordingly, the inventive formulations may optionally containantioxidant agents to provide further flux aging loss resistance.Non-limiting examples of antioxidant agents include a butylated reactionproduct of p-cresol and dicyclopentadiene antioxidant, andtetrakis-[methylene-(3,5-di-tert.-butyl-4-hydroxy-cinnamate)] methaneantioxidants.

As used herein, the term “epoxy resins” refer to synthetic uncured orunreacted resins containing epoxide functional groups with an aromaticbackbone. Non-limiting examples of epoxy resins includeepichlorohydrin/cresol novolac epoxy resin and epichlorohydrin/bisphenolA epoxy resin types. The epoxy-based coated powders with the specialtyadditives (e.g., coupling agents, antioxidants, etc.) are in the uncuredstate prior to the manufacture of the final cured magnets.

It has been discovered that coupling agents allow protection by way ofaltering the powders surface through beneficial chemical or weakerphysical (hydrogen) bonding. It is believed that the coupling agentsform protective layers on the powder that are compatible and potentiallyreactive, if appropriately selected, with the surrounding organicpassivation coating, permitting additional interaction between thecomponents of the magnet. The preferred coupling agents for applicationin the invention provide thermal stability to the magnet and limitoxidation.

Organosilane coupling agents have been used extensively fororganic-inorganic systems within aqueous and/or alcohol-rich solutions,due to their reactivity with surface hydroxyl chemical groups present onfiller particles such as glass fibers, metal hydroxides, silica andsilicates. A monolayer of reacted organosilane is formed on the fillersurface through condensation, following the hydrolysis reaction inwater.

The amine-based silanes, or aminosilanes, are among the most commonlyused silanes, due to the high reactivity between the lone pair electronsthat reside on a nitrogen atom of primary, secondary and tertiary aminesand the epoxide functional group of epoxy resins. The aforementionedreaction of the silane with the inorganic filler particle couples thosetwo entities together, and the epoxy-amine reaction establishes a bondbetween the silane and epoxy resin. Ultimately, this creates acrosslinked structure involving every reactable component of the system.

Due to their greater coupling effect and ease of reaction with fillerparticles in the absence of a solvent, organotitanate andorganozirconates (which have similar reaction mechanisms) have receivedmore attention than organosilanes in some respects. The organosilanesoffer typically a single coupling site on the molecule with a singlehydroxyl group on the filler particle, depending upon the extent of thehydrolysis and condensation reactions during pretreatment. Theorganotitanates or organozirconates allow at best three coupling sites,giving rise to more complete coverage of a monolayer. In addition tothis information, organotitanates can also react with surface protons ofinorganic filler particulates that may be devoid of hydroxyl groups. Theorganotitanate or organozirconate is also found to aid in the curingprocess to create the bonded magnet, possibly by aiding in thecross-linking process. These agents can be applied to filler surfacesvia solvent-blending or direct melt-blending processes with the polymerbinder and inorganic filler within a compounder or injection molder,which require no pretreatment. This invention focuses on thesolvent-blending or liquid coating method of application.

Because of the efficiency of these organic coupling agents,concentrations that range between 0.1 and 1.0% (by weight) aresufficient for optimal properties (e.g. enhanced processing, mechanicalstrength, adhesion, and chemical resistance). This statement isparticularly important for the manufacture of polymer-bonded magnets.The more coupling agents added to the system, then the lower thepotential magnetic strength of the magnet will be, since the magneticflux is directly related to the amount of magnetic material present. Theuse of small amounts of the coupling agents allows appropriate couplingwith minimal reduction of magnetic properties. Typical thicknesses ofcoupling agents are on the order of one micron at these concentrationsmentioned.

New materials are being added to polymeric systems called “nanofillers”or “nanoadditives” and are showing remarkable improvements in a system'sthermal stability, mechanical strengths, oxygen permeability andprocessability. These additives are primarily inorganic and consist of asilica-based structure with organic functionalities. At least one of thespatial dimensions of said nanofillers is of the nanometer range (0.001to 0.1 microns). With this minute dimension the aspect ratios tend to beon the order of 100 to 1000, which give rise to the mentionedimprovements in overall properties. Typical concentrations of thesenanofillers can vary within 0.1 to 10.0% by weight relative to thepolymer binder. Examples of a currently used nanofiller material areclay fillers (typically bentonite or montmorillonite). This material ismodified, for example, with alkyl ammonium salts in order to guaranteeproper compatibility with the matrix material. These “organoclays” are apopular new addition to the growing field of polymer nanocomposites forboth thermosetting and thermoplastic systems. Specifically forthermosets, organoclays have been effectively incorporated eitherthrough high-shear melt or solvent blending. Effective dispersion of theorganoclays' silicate layers throughout the polymer phase yieldsfavorable property enhancement.

Another family of the nanofillers distinction that has lately receivedmuch attention has the general name of polyhedral oligomericsilsesquioxanes or POSS. Polyhedral oligomeric silsesquioxanes or POSSare referred to herein as “POSS additives.” These compounds arecomprised of nano-sized silica-based cages with a vast number of organicfunctionalities. Proper selection of the most appropriate functionality,whether reactive or inert, can allow many polymeric systems to becomehybridized into unique polymer nanocomposites.

Through liquid coating with the organotitanates and/or organozirconates,nanofillers (e.g., organoclays, POSS additives) and antioxidants in thepresence of an epoxy resin, dicyandiamide hardener, tertiary amineaccelerator, and zinc stearate lubricant, the present invention providesa high-volume fraction bonded magnet by way of compression or compactionmolding. The methods of the present invention retain the organotitanatecoupling agent in the mixture during and after the steps of mixing thecoating compositions with the magnet powder, as it is found that suchintimate mixing between organotitanate and various components aids inyielding epoxy-bonded magnets with enhanced performance, such asimproved flux aging loss. In specific embodiments of the presentinvention, the organotitanate or organozirconate coupling agent areadmixed with the other constituents of the coating formulation. In otherembodiment of the invention, the organotitanate or organozirconatecoupling agent can be added to the magnet powder in a pre-coating stepbefore introduction of the other constituents of the coatingformulation.

The addition of accelerator in the coating formulations of the presentinvention reduces the curing temperature for creating the bonded magnetfrom a temperature on the order of around 200° C. or more to atemperature of around 170° C. The lower curing temperature reduces thepossibility of oxidation of the magnet material during the formation ofthe bonded magnet. This is beneficial for providing a bonded magnet witha lower flux aging loss, and better performance.

The addition of the lubricant results in lower ejection pressures forremoving the bonded magnet from the die press, which helps prolong thelife of the die press.

The present invention also provides a coating formulation applicable torare earth-transition metal-boron (RE-TM-B) magnet powders, such asneodymium-iron-boron type magnetic powders manufactured from rapidsolidification processes for, among other things, the purpose ofcorrosion and oxidation resistance when exposed to aggressiveenvironments. The coating formulation preferably contains an epoxybinder, curing agent, an accelerating agent, and a lubricant. Byincorporating coupling agents and optionally, other specialty additiveswith the magnetic powder and the organic epoxy components additionaloxidation and corrosion prevention, enhanced adhesion and dispersionbetween the filler and matrix phases can be achieved. This invention isapplicable to all such rare earth-transition metal-boron (RE-TM-B)magnet powders produced by rapid solidification and encompasses both thebonded magnet products that consist of combinations of the materialsmentioned and the application processes. Experimental testing of themagnets of the present invention revealed the exceptional propertiesderived from the coating formulations of the invention.

Solvent or liquid coating is an effective manner in which each organiccomponent can be blended with solid filler particles. It has beendiscovered that applying a low-viscosity, volatile carrier fluidcontaining dissolved low-molecular weight binder components andadditives effectively allows the deposition of a protective, organiclayer on the magnetic powders under ambient or moderate-temperatureconditions. This procedure ensures a fast and simple production ofcompression moldable, liquid-coated, RE-TM-B powders forhigh-temperature applications.

In another aspect, the present invention provides rapidly solidifiedrare earth-transition metal-boron (RE-TM-B) type magnetic materials witha protective passivation coating for high temperature and aggressiveenvironment exposure. The bonded magnets are formed from the coatedmagnetic powders that have been compacted and subsequently cured. Theresulting bonded magnets, that arise from the liquid coating process,including organotitanate coupling agents in the epoxy system, showsignificant improvement in flux loss aging as compared to magnets madewithout coupling agent at temperatures or exceeding 180° C. FIG. 1 showsthe stark contrast in flux aging loss at 180° C. after 100 hours betweenmagnets (operating at a load line PC=2) formulated in the absence ofcoupling agents (No CA) or that have been liquid-coated with anorganotitanate or organozirconate agent (LICA 38, KZ OPPR, KR 55). Thepresence of the organic coupling agent reduces the degree of oxidationof these powders, making them suitable for numerous hightemperature/corrosive environment applications. Five embodiments of thepresent invention are disclosed, including one non-coupled magneticpowder system and four coupled magnetic powder systems for passivation.The exemplary coupled systems include a coupling agent-coated powder, acoupling agent-epoxy-coated powder and two couplingagent-nanoadditive-coated powders.

In many embodiments, the present invention provides a magnetic materialthat has been rapidly solidified then thermally annealed, preferablywithin the temperature range of 300° C. to 800° C. for about 0.5 toabout 120 minutes. The magnetic material has the composition, in atomicpercentage, of R_(u)Fe_(100-u-v-w-x-y)Co_(v)M_(w)B_(x), wherein R is anyrare earth element including yttrium; M is one or more of Zr, Nb, Ti,Cr, V, Mo, W, Hf, Al, Mn, Cu, and Si. Further, the values for u, v, wand x are as follows: 7≦u≦13, 0≦v≦20, 0≦w≦7 and 4≦x≦10. In addition, themagnetic material exhibits a remanence (B_(r)) value from about 6 toabout 12 kG and an intrinsic coercivity (H_(ci)) value from about 5.0 toabout 15 kOe.

Any number of thermosetting polymer binders may be selected, such as,urea formaldehyde (amino resins), phenolics, thermosetting polyurethaneresins, alkyd resins, or epoxy resins. Curing agents or hardenerscontain functional groups that react with functional groups of the resinand are required to cause the crosslinking or cure reaction. Examples ofcuring agents are aliphatic (linear), cycloaliphatic, tertiary, andaromatic amines; amine adducts; amidoamines; polyamides; or anhydrides.Typically, these agents are added to the resin at about 1 to 6 phr (perhundred parts resin), depending on the desired extent of cure of thefinal crosslinked product. The accelerator, which increases thereactivity of the curing agent, can be a tertiary amine, e.g. imidazole,amine adduct, or amine-based complex, e.g. BF₃ mono-ethylamine complex.Accelerator concentrations fall within the range of 1 to 4 phr. For easeof processing, a lubricant such as fatty acids, metal (e.g., zinc orcalcium) stearates, fluoropolymer resins, polyolefin or polyesterresins, etc. is used. Typically lubricants are measured relative to theamount of solid filler present. The concentration range of lubricant maybe 0.01 to 0.5 phf (per hundred parts filler) and is dependent on thedesired final properties of the resulting bonded magnet. Antioxidantconcentrations tend to exist within the range of 0.5 to 1.5 phr (perhundred parts resin), and are useful for oxygen radical consumption in asystem.

The appropriate amounts of coupling agent and nanofiller (e.g.,organoclay and POSS additive) for a specific system are determinedempirically for optimization of its final desired magnet properties.Preferably the concentration ranges of coupling agent, organoclays andPOSS additive added to the entire system should fall within 0.1 to 1.0%by weight (based on amount of binder and filler), 1.0 to 10.0% by weight(based on amount of resin), and 0.1 to 1.0% by weight (based on amountof binder and filler), respectively.

In a specific embodiments, a multifunctional epichlorohydrin/cresolnovolac epoxy resin, with a dicyandiamide curing agent, a tertiary amineaccelerator and zinc stearate lubricating agent in the polymer bindersystem are used for compression-molding purposes both including andexcluding coupling agent. Any of the following coupling agents areapplicable to this invention: organosilanes, organotitanates,organozirconates, and organozircoaluminates. For these embodiments therecommended coupling agents for the epoxy-bonded RE-TM-B magnets are theorganotitanates and organozirconates, which are of the general form(RO—)_(n)Ti(—OXR′Y)_(4-n)and(RO—)_(n)Zr(—OXR′Y)_(4-n)

The RO is the hydrolyzable group that reacts with surface protons orhydroxyl groups, where R may be short or long chained alkyls(monoalkoxy) or unsaturated allyls (neoalkoxy). Ti and Zr are typicallytetravalent titanium and zirconium atoms, respectively, where both mayhave higher or lower valence as well. X is the binder functional groups,such as phosphato, phosphito, pyrophosphato, sulfonyl, carboxyl, etc. R′is the thermoplastic functional group such as: aliphatic and non-polarisopropyl, butyl, octyl, isostearoyl groups; napthenic and mildly polardodecylbenzyl groups; or aromatic benzyl, cumyl phenyl groups. Y is thethermosetting functional group that typically is reactive, e.g. amino orvinyl groups. n represents the functionality of the molecule. Afunctionality of n=2 implies that there exist two reactive hydrolyzablegroups and two organofunctional groups for compatibility with thepolymer binder. Examples of the various functionalities of thesecoupling agents are displayed in Table 1. The liquid coupling agentorganotitanates and organozirconates with pyrophosphato and phosphitobinder functional groups were found to be most effective for oxidationresistance, due to their reactive nature with surface protons andhydroxyls present on the magnetic powders surfaces.

TABLE 1 Functional groups of organotitanate and organozirconate couplingagents Titanate Symbol Chemical Group Chemical Name Type n R (CH₃)₂—H

— isopropyl monoalkoxy  1-4^(†) H₃

— methyl monoalkoxy 1 C₇H₁₅—H₂

— octyl alkoxy 1-4 CH₃CH₂C(CH₂OCH₂CH═CH₂)—H₂

— 2,2-diallyloxymethyl allyloxy 4 CH₂═CHCH₂OCH₂ CH₃CH₂C—H₂

— neopentyl(diallyl)oxy neoalkoxy 1 CH₂═CHCH₂OCH₂ R′, X, Y —(

═O)C₁₇H₃₅ isostearoyl monoalkoxy 3 —(

═O)

(CH₃)═CH₂ methacryl monoalkoxy 2-3 —(O═

═O)—AR—C₁₂H₂₅ dodecylbenzenesulfonyl monoalkoxy 3 —(HO—

═O)—O—(

═O)—(C₈H₁₇)₂ pyrophosphato neoalkoxy 3 ^(†)The titanium and zirconiumatoms may have coordination numbers greater than 4. AR is an aromaticbenzene unit. The italicized, bold-type atom is the primary connectingatom of the functional segment. Information taken from Ken ReactReference Manual.

The liquid coating process requires an appropriate solvent for properdissolution of the organic resin, hardener, accelerator, lubricant andcoupling agent. Polar protic solvents, such as, alkanols or alkoxy-basedalcohols and aprotic solvents, such as, ketones, aromatics, andglycol-based ethers are useful for epoxy resin dissolution. Proticsolvents may not always be advisable, due to the possible side reactionof a proton-donating solvent molecule with the epoxide group of theresin monomer. Since most amine-based curing agents and accelerators arepolar molecules, the aforementioned solvents could be appropriate forthese components. Stearates or fatty acids are also polar since theycontain the carboxylate ion. Many of the organotitanates andorganozirconates can vary in solubility with particular solvents. Thepyrophosphato-, phosphate-, and phosphito-functionaltitanates/zirconates, due to their aprotic polarity, have very goodsolubility in the following solvents: isopropanol, xylene, toluene,dioctyl phthalate and ketones. Other coupling agents of differentfunctionality may have limited solubility in most conventional solvents.When using the recommended components in this invention, acetone hasproven to be a very acceptable carrier fluid, for both coupled andnon-coupled systems, because of its ability to dissolve the ingredientswell and high vapor pressure at ambient temperature.

Various embodiments of the invention contain and/or require a propermixing procedure in order to obtain optimal characteristics. In thefirst embodiment of the present invention, the RE-TM-B magnet powdersare coated with a homogeneous solution of the epichlorohydrin/cresolnovolac epoxy resin, a dicyandiamide curing agent, a tertiary amineaccelerator and zinc stearate lubricating agent in acetone. Once addedto the organics solution, mixing of the RE-TM-B magnet powders continueswhile the mixture is heated above room temperature for solvent removal.

In the second embodiment of the present invention, a coupling agent isincorporated with the RE-TM-B magnet powders through a precoatingprocess. An organotitanate-acetone solution is added to the magneticpowders and stirred followed by the subsequent evaporation of acetone.The pretreated RE-TM-B powders are then subjected to the mixingprocedure as in the first embodiment that includes the epoxy systemorganic components.

In the third embodiment of the present invention, the organotitanatecoupling agent is incorporated with the RE-TM-B magnet powders and theepoxy system organic components through an admixing process. The RE-TM-Bmagnet powders are blended with a homogeneous acetone solution of theepichlorohydrin/cresol novolac epoxy resin, a dicyandiamide curingagent, a tertiary amine accelerator, zinc stearate lubricating agent,and the coupling agent. The relative amounts of the resin, curing agent,accelerator and lubricant are reduced accordingly in order to maintainan RE-TM-B powder mass percent of 98.3% when incorporating the couplingagent. FIG. 2 shows a plot of the flux aging loss results for curedmagnets according to the first, second and third embodiments of thepresent invention.

As can be seen in FIG. 2, the magnetic material according to the secondembodiment (Precoated CA) exhibits improved properties over the magneticmaterial of the first embodiment (No CA) due to the incorporation of thecoupling agent (CA) through precoating the magnet powders. Furthermore,an enhancement of the flux aging loss of the RE-TM-B powders is attainedwhen the organotitanate is admixed with the epoxy system components, asseen in FIG. 2 for the third embodiment (Admixed CA).

The magnetic material according to the fourth embodiment of the presentinvention has a similar formulation to the magnetic material of thethird embodiment, but differs due to the addition of bentonite claypowder that has been chemically treated to contain bis (hydroxyethyl)methyl tallow alkyl ammonium salts within the admixing acetone solution.The relative amounts of the resin, curing agent, accelerator andlubricant are reduced accordingly in order to maintain a magnetic powderweight percent of 97.6% when incorporating the organoclays. FIG. 3 showsa plot of the flux aging loss results for cured magnets according to thefirst and fourth embodiments of the invention. The incorporation of theadditive of the treated bentonite clay powder within the admixingacetone solution results in a significant improvement in the flux lossof the magnetic material according to the fourth embodiment as comparedto the first embodiment.

The magnetic material according to the fifth embodiment of the presentinvention has a similar formulation to the magnetic material of thefourth embodiment, but differs due to the initial precoating of asilanol-POSS with phenyl group functionality on the magnetic powders. APOSS-tetrahydrofuran (THF) solution is added and then stirred with themagnetic powders, followed by the evaporation of the THF solvent. Thepretreated powders are then subjected to the mixing procedure in thefourth embodiment with admixing the organics-acetone solution. Therelative amounts of the resin, curing agent, accelerator and lubricantare reduced accordingly in order to maintain a magnetic powder weightpercent of 97.6% when incorporating the organoclays. FIG. 4 shows theimproved flux aging loss results for cured magnets according to thefifth embodiment as compared to the cured magnets of the first and thirdembodiments.

EXAMPLES Example 1

Commercially available MQP™-B powder is liquid-coated with anepichlorohydrin/cresol novolac epoxy resin EPON 164™ (Shell ChemicalCompany), dicyandiamide curing agent (SKW Trostberg), a tertiary amineaccelerator, Fenuron™, (SKW Trostberg), and zinc stearate in a 8%acetone solution. The resin, curing agent, accelerator, and zincstearate are added together with the acetone in a glass 500 mL beaker.The mixture is stirred periodically in order to produce a homogeneoussolution of the organic components. The MQP™-B powder is subsequentlyadded to the solution, allowing the addition of more acetone tosufficiently immerse the powders in the solution (roughly 1 mL ofacetone per 5 grams of MQP powder). The overall proportions andcompositions of the components are shown in Table 1a. The beakercontaining the mixture is then placed on a hot plate and heated at 50°C. The contents are periodically stirred while the acetone evaporates.For complete drying the powders are removed from the beaker and spreadevenly on a flat surface within a fume hood.

TABLE 1A Component Mass (g) Weight Percent (%) Example 1 MQP ™-B 100.098.272 EPON 164 Resin 1.600 1.572 Dicyandiamide 0.096 0.094 Accelerator0.032 0.031 Zinc Stearate 0.030 0.029

Example 2

Commercially available MQP™-B powder is liquid-coated with 0.6% LICA 38™(Kenrich Petrochemicals, Inc.) (see Table 2). The coupling agent isadded to acetone in a glass 500 mL beaker creating a 50% solution. TheMQP™-B powder is added to the solution, allowing the addition of moreacetone to sufficiently immerse the powders in the solution. Thecompositions of the components are shown in Table 3. The beakercontaining the mixture is then placed on a hot plate and is heated at50° C. The contents are periodically stirred while the acetoneevaporates. For complete drying the powders are removed from the beakerand spread. evenly on a flat surface within a fume hood.

TABLE 2 Organotitanate/Organozirconate Coupling agent NomenclatureCoupling Agent Chemical Name LICA 38 ™neopentyl(diallyl)oxy-tri(dioctyl) pyrophophato titanate KR 55 ™tetra(2,2-diallyoxymethyl)butyl- di(ditridecyl)phosphito titanate KR238M ™ methacrylate functional amine adduct of di(dioctyl)pyrophosphateethylene titanate KZ OPPR ™ cyclo (dioctyl) pyrophosphato dioctylzirconate SIA0610 ™ γ-aminopropyltriethoxysilane

TABLE 3 Composition of Example 2 Component Mass (g) Weight Percent (%)Example 2 MQP ™-B 100.0 99.393 LICA 38 ™ 0.611 0.607

Example 3

Commercially available MQP™-B powder is pre-coated with LICA 38™(Kenrich Petrochemicals, Inc.) before further liquid-coating with anepichlorohydrin/cresol novolac epoxy resin EPON 164™ (Shell ChemicalCompany), dicyandiamide curing agent (SKW Trostberg), a tertiary amineaccelerator, FenuronTm, (SKW Trostberg), and zinc stearate in a 8%acetone solution. The coupling agent is added together with the acetonein a glass 500 mL beaker in a 50/50 solution. The mixture is stirredperiodically in order to produce a homogeneous solution of the organiccomponents. The MQP™-B powder is subsequently added to the solution,allowing the addition of more acetone to sufficiently immerse thepowders in the solution. The overall proportions and compositions of thepowder and coupling agent are shown in Table 3. The beaker containingthe mixture is then placed on a hot plate and is heated at 50° C. Thecontents are periodically stirred while the acetone evaporates. Forcomplete drying the powders are removed from the beaker and spreadevenly on a flat surface within a fume hood. Following the drying step,the precoated powders are added to the 8% acetone solution with epoxyresin, curing agent, accelerator, and zinc stearate. The acetone is thenallowed to evaporate while the powder-organics-acetone mixture isperiodically stirred. Table 4 shows the respective amounts of eachcomponent.

TABLE 4 Compositions of Example 3 and 4 Component Mass (g) WeightPercent (%) Examples 3 and 4 MQP ™-B 100.0 98.272 EPON 164 Resin 1.0441.026 Dicyandiamide 0.063 0.062 Accelerator 0.021 0.021 Zinc Stearate0.020 0.019 LICA 38 ™ 0.611 0.600

Example 4

Commercially available MQP™-B powder is admixed with LICA 38™ (KenrichPetrochemicals, Inc.), an epichlorohydrin/cresol novolac epoxy resinEPON 164™ (Shell Chemical Company), dicyandiamide curing agent (SKWTrostberg), a tertiary amine accelerator, Fenuron™, (SKW Trostberg), andzinc stearate in a 8% acetone solution. The resin, curing agent,accelerator, zinc stearate and titanate are added together with acetonein a glass 500 mL beaker, creating a 8% organics solution. The mixtureis stirred periodically in order to produce a homogeneous solution ofthe organic components. The MQP™-B powder is subsequently added to thesolution, allowing the addition of more acetone to sufficiently immersethe powders in the solution (see Table 4 for compositions). The beakercontaining the mixture is then placed on a hot plate and is heated at50° C. The contents are periodically stirred while the acetoneevaporates. For complete drying the powders are removed from the beakerand spread evenly on a flat surface within a fume hood. FIG. 1 shows theflux aging loss results of magnets following this recipe compared toother organotitanates or organozirconates or no coupling agent at all.FIG. 2 shows a comparison of the products of the liquid-coating methodsin the absence of a coupling agent (Example 1), precoated MQP™-B withcoupling agent (Example 3), and admixed MQP™-B with coupling agent, asdescribed in the first and second embodiments of the invention.

This method is also performed under the same conditions by usingMQP™-14-12 powders. FIG. 5 displays the flux aging results at varioustemperatures for MQP™-14-12 magnets in the absence of comprised of LICA38™ (No LICA), and including 0.6% LICA 38™.

Example 5

Commercially available MQP™-B powder is admixed with KR 55™ (KenrichPetrochemicals, Inc.), an epichlorohydrin/cresol novolac epoxy resinEPON 164™ (Shell Chemical Company), dicyandiamide curing agent (SKWTrostberg), a tertiary amine accelerator, Fenuron™, (SKW Trostberg), andzinc stearate in a 8% acetone solution. The resin, curing agent,accelerator, zinc stearate and titanate are added together with acetonein a glass 500 mL beaker, creating a 8% organics solution. The mixtureis stirred periodically in order to produce a homogeneous solution ofthe organic components. The MQP™-B powder is subsequently added to thesolution, allowing the addition of more acetone to sufficiently immersethe powders in the solution (see Table 5 for compositions). The beakercontaining the mixture is then placed on a hot plate and is heated at50° C. The contents are periodically stirred while the acetoneevaporates. For complete drying the powders are removed from the beakerand spread evenly on a flat surface within a fume hood. FIG. 1 shows theflux aging loss results of magnets following this recipe compared toother organotitanates or organozirconates or no coupling agent at all.

TABLE 5 Compositions of Example 5 Component Mass (g) Weight Percent (%)Example 5 MQP ™-B 100.0 98.272 EPON 164 Resin 1.137 1.117 Dicyandiamide0.068 0.067 Accelerator 0.023 0.022 Zinc Stearate 0.021 0.021 KR 55 ™0.509 0.500

Example 6

Commercially available MQP™-B powder is admixed with KZ OPPR™ (KenrichPetrochemicals, Inc.), an epichlorohydrin/cresol novolac epoxy resinEPON 164™ (Shell Chemical Company), dicyandiamide curing agent (SKWTrostberg), a tertiary amine accelerator, Fenuron™, (SKW Trostberg), andzinc stearate in a 8% acetone solution. The resin, curing agent,accelerator, zinc stearate and titanate are added together with acetonein a glass 500 mL beaker, creating a 8% organics solution. The mixtureis stirred periodically in order to produce a homogeneous solution ofthe organic components. The MQP™-B powder is subsequently added to thesolution, allowing the addition of more acetone to sufficiently immersethe powders in the solution (see Table 6 for compositions). The beakercontaining the mixture is then placed on a hot plate and heated at 50°C. The contents are periodically stirred while the acetone evaporates.For complete drying the powders are removed from the beaker and spreadevenly on a flat surface within a fume hood. FIG. 1 shows the flux agingloss results of magnets following this recipe compared to otherorganotitanates or organozirconates or no coupling agent at all.

TABLE 6 Compositions of Example 6 Component Mass (g) Weight Percent (%)Example 6 MQP ™-B 100.0 98.272 EPON 164 Resin 1.137 1.117 Dicyandiamide0.068 0.067 Accelerator 0.023 0.022 Zinc Stearate 0.021 0.021 KZ OPPR ™0.509 0.500

Example 7

Commercially available MQP™-B powder is pretreated in a 0.5% aqueoussolution of the aminosilane SIA0610™ (Gelest). The powders are stirredfor 10 minutes, and then they are placed in an oven at 110° C. for 30minutes followed by drying under a fume hood for 24 hours. An 8%solution of an epichlorohydrin/cresol novolac epoxy resin EPON 164™(Shell Chemical Company), dicyandiamide curing agent (SKW Trostberg), atertiary amine accelerator, Fenuron™, (SKW Trostberg), and zinc stearatein a acetone is prepared in a glass 500 mL beaker. Stirring of themixture is performed periodically in order to produce a homogeneoussolution of the organic components. The dry silane-coated powders aresubsequently added to the acetone solution, allowing the addition ofmore acetone to sufficiently immerse the powders in the solution. Theoverall proportions and compositions of the components are shown inTable 7. The beaker containing the mixture is then placed on a hot plateand heated at 50° C. The contents are periodically stirred while theacetone evaporates. For complete drying the powders are removed from thebeaker and spread evenly on a flat surface within a fume hood. FIG. 6shows a comparison the flux aging loss of untreated (uncoupled) MQP™-Band SIA0610-coated MQP™-B that have been subjected to the liquid-coatingprocess.

TABLE 7 Compositions of Example 7 Component Mass (g) Weight Percent (%)Example 7 MQP ™-B 100.0 98.272 EPON 164 Resin 1.137 1.550 Dicyandiamide0.068 0.094 Accelerator 0.023 0.031 Zinc Stearate 0.021 0.029 SIA0610 ™0.031 0.030

Example 8

Commercially available MQP™-B powder is admixed with organotitanate LICA38™ (Kenrich Petrochemicals, Inc.), an epichlorohydrin/cresol novolacepoxy resin EPON 164™ (Shell Chemical Company), dicyandiamide curingagent (SKW Trostberg), a tertiary amine accelerator, Fenuron™, (SKWTrostberg), zinc stearate, and organoclay Cloisite 30B™ (Southern ClayProducts) in a 8% acetone solution. The resin, curing agent,accelerator, zinc stearate, organotitanate, and organoclay are addedtogether with acetone in a glass 500 mL beaker. The mixture is stirredperiodically in order to produce a homogeneous solution of the organiccomponents. The MQP™-B powder is subsequently added to the solution,allowing the addition of more acetone to sufficiently immerse thepowders in the solution (see Table 8 for compositions). The beakercontaining the mixture is then placed on a hot plate and heated at 50°C. The contents are periodically stirred while the acetone evaporates.For complete drying the powders are removed from the beaker and spreadevenly on a flat surface within a fume hood.

TABLE 8 Composition of Example 8 Component Mass (g) Weight Percent (%)Example 8 MQP ™-B 100 97.605 EPON 164 Resin 1.457 1.422 Dicyandiamide0.087 0.085 Accelerator 0.029 0.028 Zinc Stearate 0.091 0.089 LICA 38 ™0.615 0.600 Cloisite 30B ™ 0.175 0.171

Example 9

Commercially available MQP™-B powder is precoated with atrisilanolphenyl POSS™ additive (Hybrid Plastics) before furtherliquid-coating with an epichlorohydrin/cresol novolac epoxy resin EPON164™ (Shell Chemical Company), dicyandiamide curing agent (SKWTrostberg), a tertiary amine accelerator, Fenuron™, (SKW Trostberg),zinc stearate, an organotitanate LICA 38™ (Kenrich Petrochemicals, Inc.)an organoclay Cloisite 30B™ (Southern Clay Products), and an antioxidantRalox LC™ (Degussa, butylated reaction product of p-cresol anddicyclopentadiene) in a 8% acetone solution. The resin, curing agent,accelerator, zinc stearate, organotitanate, organoclay and antioxidantare added together with acetone in a glass 500 mL beaker. The mixture isstirred periodically in order to produce a homogeneous solution of theorganic components. The MQP™-B powder is subsequently added to thesolution, allowing the addition of more acetone to sufficiently immersethe powders in the solution (see Table 9 for compositions). The beakercontaining the mixture is then placed on a hot plate and heated at 50°C. The contents are periodically stirred while the acetone evaporates.For complete drying the powders are removed from the beaker and spreadevenly on a flat surface within a fume hood.

TABLE 9 Composition of Example 9 Component Mass (g) Weight Percent (%)Example 9 MQP ™-B 100.0 97.605 EPON 164 Resin 1.050 1.025 Dicyandiamide0.063 0.061 Accelerator 0.021 0.020 Zinc Stearate 0.066 0.064 LICA 38 ™0.130 0.490 Cloisite 30B ™ 0.615 0.600 Trisilanolphenyl POSS ™ 0.5000.123 Ralox LC ™ 0.011 0.011

Miscellaneous

Many modifications and variations of this invention can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

References Cited

All references cited herein are incorporated herein by reference intheir entirety and for all purposes to the same extent as if eachindividual publication or patent or patent application was specificallyand individually indicated to be incorporated by reference in itsentirety for all purposes.

1. A rapidly solidified rare earth-transition metal-boron magnetmaterial, comprising a coated rare earth-transition metal-boron magnetpowder comprising the magnet powder and a coating formulation, whereinthe coating formulation comprises a combination, in an amount by weightof the magnet powder, of about 0.1 weight percent to about 1 weightpercent of an organotitanate or organozirconate coupling agent, about0.18 weight percent to about 4.46 weight percent of an epoxy resin,about 0.01 weight percent to about 0.27 weight percent of an amine-basedhardener, about 0.004 weight percent to about 0.09 weight percent of anaccelerator, and about 0.003 weight percent to about 0.27 weight percentof a lubricant; wherein the general form of the coupling agent is(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n) where R is a neopentyl(diallyl),dioctyl, or (2,2-diallyloxymethyl)butyl group, Ti or Zr has acoordination number of 4, R′ is a phosphito, pyrophosphato or cyclicpyrophosphato segment, and Y is a dioctyl or ditridecyl end group with1≦n≦4.
 2. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 1, wherein said coating formulation comprisesabout 0.1 weight percent to about 1 weight percent of the organotitanateor organozirconate coupling agent, about 0.43 weight percent to about 3weight percent of the epoxy resin, about 0.025 weight percent to about0.18 weight percent of the amine-based hardener, about 0.009 weightpercent to about 0.06 weight percent of the accelerator, and about 0.009weight percent to about 0.19 weight percent of the lubricant.
 3. Arapidly solidified rare earth-transition metal-boron magnet materialcomprising a coated rare earth-transition metal-boron magnet powdercomprising the magnet powder and a coating formulation, wherein thecoating formulation comprises a combination, in an amount by weight ofthe magnet powder, of about 0.225 weight percent to about 4.25 weightpercent of epichlorohydrin/cresol novolac epoxy resin, about 0.01 weightpercent to about 0.26 weight percent of dicyandiamide hardener, about0.005 weight percent to about 0.085 weight percent of an aromatic,tertiary amine accelerator, about 0.004 weight percent to about 0.27weight percent of zinc stearate lubricant, and about 0.35 weight percentto about 0.75 weight percent of an organotitanate coupling agent of theform(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 4. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 3, wherein said coating formulation comprisesabout 0.68 weight percent to about 2.76 weight percent ofepichlorohydrin/cresol novolac epoxy resin, about 0.04 weight percent toabout 0.17 weight percent of dicyandiamide hardener, about 0.01 weightpercent to about 0.055 weight percent of the aromatic, tertiary amineaccelerator, about 0.01 weight percent to about 0.175 weight percent ofthe zinc stearate lubricant.
 5. A rapidly solidified rareearth-transition metal-boron magnet material, comprising a coated rareearth-transition metal-boron magnet powder comprising the magnet powderand a coating formulation, wherein the coating formulation comprises acombination, in an amount by weight of the magnet powder, of about 0.65weight percent to about 2.5 weight percent of an epoxy resin, about0.035 weight percent to about 0.15 weight percent of an amine-basedhardener, about 0.01 weight percent to about 0.05 weight percent of anaccelerator, about 0.04 weight percent to about 0.16 weight percent of alubricant, about 0.001 weight percent to about 0.3 weight percent of anorganoclay, and about 0.35 weight percent to about 0.75 weight percentof an organotitanate or organozirconate coupling agent of the generalform(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n) where R is a neopentyl(diallyl),dioctyl, or (2,2-diallyoxymethyl)butyl group, Ti or Zr has acoordination number of 4, R′ is a phosphito, pyrophosphato or cyclicpyrophosphato segment, and Y is a dioctyl or ditridecyl end group with1≦n≦4.
 6. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 5, wherein the coupling agent is anorganotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 7. The rapidly solidified rare earth-transition metal-boronmaterial of claim 5, wherein: the epoxy resin is epichlorohydrin/cresolnovolac epoxy resin, the amine-based hardener is dicyandiamide hardener,the accelerator is an aromatic, tertiary amine accelerator, thelubricant is zinc stearate; and the organoclay comprises bis(hydroxyethyl) methyl tallow alkyl ammonium salts with bentonite.
 8. Therapidly solidified rare earth-transition metal-boron magnet material ofclaim 5, wherein said coating formulation comprises about 0.001 weightpercent to about 0.3 weight percent of an organoclay comprising bis(hydroxyethyl) methyl tallow alkyl ammonium salts with bentonite; andabout 0.35 weight percent to about 0.75 weight percent of anorganotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 9. A rapidly solidified rare earth-transition metal-boron magnetmaterial comprising a coated rare earth-transition metal-boron magnetpowder, comprising a pre-coated magnet powder and a coating formulation,wherein the pre-coated magnet powder comprises a combination of themagnet powder with a pre-coating of a POSS additive present in an amountby weight of the magnet powder of about 0.1 weight percent to about 5weight percent; and wherein the coating formulation comprises acombination, in an amount by total weight of the coating formulation, ofabout 0.54 weight percent to about 2.75 weight percent of an epoxyresin, about 0.03 weight percent to about 0.17 weight percent of anamine-based hardener, about 0.01 weight percent to about 0.06 weightpercent of an accelerator, about 0.035 to about 0.175 weight percent ofa lubricant, about 0.35 weight percent to about 0.75 weight percent ofan organotitanate or organozirconate coupling agent of the general form(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n) where R is a neopentyl(diallyl),dioctyl, or (2,2-diallyloxymethyl)butyl group, Ti or Zr has acoordination number of 4 or 5, R′ is a phosphito, pyrophosphato orcyclic pyrophosphato segment, and Y is a dioctyl or ditridecyl endgroup, with 1≦n≦4, about 0.003 weight percent to about 0.055 weightpercent of an organoclay, and about 0.003 weight percent to about 0.015weight percent of an antioxidant agent.
 10. The rapidly solidified rareearth-transition metal-boron magnet material of claim 9, wherein thecoupling agent is an organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 11. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 9, wherein the POSS additive istrisilanolphenyl or epoxycyclohexyl POSS.
 12. The rapidly solidifiedrare earth-transition metal-boron magnet material of claim 9, whereinthe antioxidant agent is a butylated reaction product of p-cresol anddicyclopentadiene antioxidant.
 13. The rapidly solidified rareearth-transition metal-boron magnet material of claim 9, wherein: theepoxy resin is epichlorohydrin/cresol novolac epoxy resin, theamine-based hardener is dicyandiamide hardener, the accelerator is anaromatic, tertiary amine accelerator, the lubricant is zinc stearatelubricant; and the organo clay additive is bis (hydroxyethyl) methyltallow alkyl ammonium salts with bentonite.
 14. The rapidly solidifiedrare earth-transition metal-boron magnet material of claim 9, wherein:said pre-coating is a trisilanolphenyl or epoxycyclohexyl POSS in anamount of about 0.1 weight percent to about 1 weight percent, by weightof the magnet powder; and said coating formulation comprises, by totalweight of the mixture, of about 0.54 weight percent to about 2.75 weightpercent of epichlorohydrin/cresol novolac epoxy resin, about 0.03 weightpercent to about 0.17 weight percent of dicyandiamide hardener, about0.01 weight percent to about 0.06 weight percent of an aromatic,tertiary amine accelerator, about 0.035 weight percent to about 0.175weight percent of zinc stearate lubricant, about 0.35 weight percent toabout 0.75 weight percent of an organotitanate coupling agent of theform(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup, about 0.003 weight percent to about 0.07 weight percent of anorganoclay comprising bis (hydroxyethyl) methyl tallow alkyl ammoniumsalts with bentonite, and about 0.003 weight percent to about 0.015weight percent of a butylated reaction product of p-cresol anddicyclopentadiene antioxidant.
 15. A rapidly solidified rareearth-transition metal-boron magnet material, comprising a coated rareearth-transition metal-boron magnet powder comprising the magnet powderand a coating formulation, wherein the coating formulation comprises acombination consisting essentially of, in an amount by weight of themagnet powder, of about 0.1 weight percent to about 1 weight percent ofan organotitanate or organozirconate coupling agent, about 0.18 weightpercent to about 4.46 weight percent of an epoxy resin, about 0.01weight percent to about 0.27 weight percent of an amine-based hardener,about 0.004 weight percent to about 0.09 weight percent of anaccelerator, and about 0.003 weight percent to about 0.27 weight percentof a lubricant; wherein the general form of the coupling agent is(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n) where R is a neopentyl(diallyl),dioctyl, or (2,2-diallyloxymethyl)butyl group, Ti or Zr has acoordination number of 4, R′ is a phosphito, pyrophosphato or cyclicpyrophosphato segment, and Y is a dioctyl or ditridecyl end group, with1≦n≦4.
 16. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 15, wherein said coating formulation consistsessentially of about 0.1 weight percent to about 1 weight percent of theorganotitanate or organozirconate coupling agent, about 0.43 weightpercent to about 3 weight percent of the epoxy resin, about 0.025 weightpercent to about 0.18 weight percent of the amine-based hardener, about0.009 weight percent to about 0.06 weight percent of the accelerator,and about 0.009 weight percent to about 0.19 weight percent of thelubricant.
 17. A rapidly solidified rare earth-transition metal-boronmagnet material, comprising a coated rare earth-transition metal-boronmagnet powder comprising the magnet powder and a coating formulation,wherein the coating formulation comprises a combination consistingessentially of, in an amount by weight of the magnet powder, of about0.225 weight percent to about 4.25 weight percent ofepichlorohydrin/cresol novolac epoxy resin, about 0.01 weight percent toabout 0.26 weight percent of dicyandiamide hardener, about 0.005 weightpercent to about 0.085 weight percent of an aromatic, tertiary amineaccelerator, about 0.004 weight percent to about 0.27 weight percent ofzinc stearate lubricant, and about 0.35 weight percent to about 0.75weight percent of an organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 18. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 17, wherein said coating formulation consistsessentially of about 0.68 weight percent to about 2.76 weight percent ofepichlorohydrin/cresol novolac epoxy resin, about 0.04 weight percent toabout 0.17 weight percent of dicyandiamide hardener, about 0.01 weightpercent to about 0.055 weight percent of the aromatic, tertiary amineaccelerator, about 0.01 weight percent to about 0.175 weight percent ofthe zinc stearate lubricant.
 19. A rapidly solidified rareearth-transition metal-boron magnet material, comprising a coated rareearth-transition metal-boron magnet powder comprising the magnet powderand a coating formulation, wherein the coating formulation comprises acombination consisting essentially of, in an amount by weight of themagnet powder, of about 0.65 weight percent to about 2.5 weight percentof an epoxy resin, about 0.035 weight percent to about 0.15 weightpercent of an amine-based hardener, about 0.01 weight percent to about0.05 weight percent of an accelerator, about 0.04 weight percent toabout 0.16 weight percent of a lubricant, about 0.001 weight percent toabout 0.3 weight percent of an organoclay, and about 0.35 weight percentto about 0.75 weight percent of an organotitanate or organozirconatecoupling agent of the general form(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n) where R is a neopentyl(diallyl),dioctyl, or (2,2-diallyoxymethyl)butyl group, Ti or Zr has acoordination number of 4, R′ is a phosphito, pyrophosphato or cyclicpyrophosphato segment, and Y is a dioctyl or ditridecyl end group, with1≦n≦4.
 20. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 19, wherein the coupling agent is anorganotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 21. The rapidly solidified rare earth-transition metal-boronmaterial of claim 19, wherein: the epoxy resin is epichlorohydrin/cresolnovolac epoxy resin, the amine-based hardener is dicyandiamide hardener,the accelerator is an aromatic, tertiary amine accelerator, thelubricant is zinc stearate; and the organoclay comprises bis(hydroxyethyl) methyl tallow alkyl ammonium salts with bentonite. 22.The rapidly solidified rare earth-transition metal-boron magnet materialof claim 19, wherein said coating formulation consists essentially ofabout 0.001 weight percent to about 0.3 weight percent of an organoclaycomprising bis (hydroxyethyl) methyl tallow alkyl ammonium salts withbentonite; and about 0.35 weight percent to about 0.75 weight percent ofan organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 23. A rapidly solidified rare earth-transition metal-boron magnetmaterial comprising a coated rare earth-transition metal-boron magnetpowder, comprising a pre-coated magnet powder and a coating formulation,wherein the pre-coated magnet powder comprises a combination of themagnet powder with a pre-coating of a POSS additive present in an amountby weight of the magnet powder of about 0.1 weight percent to about 5weight percent; and wherein the coating formulation consists essentiallyof, in an amount my total weight of the coating formulation, of about0.54 weight percent to about 2.75 weight percent of an epoxy resin,about 0.03 weight percent to about 0.17 weight percent of an amine-basedhardener, about 0.01 weight percent to about 0.06 weight percent of anaccelerator, about 0.035 to about 0.175 weight percent of a lubricant,about 0.35 weight percent to about 0.75 weight percent of anorganotitanate or organozirconate coupling agent of the general form(RO—)_(n)(Ti or Zr)(—OR′Y)_(4-n) where R is a neopentyl(diallyl),dioctyl, or (2,2-diallyloxymethyl)butyl group, Ti or Zr has acoordination number of 4 or 5, R′ is a phosphito, pyrophosphato orcyclic pyrophosphato segment, and Y is a dioctyl or ditridecyl end groupwith 1≦n≦4, about 0.003 weight percent to about 0.055 weight percent ofan organoclay, and about 0.003 weight percent to about 0.015 weightpercent of an antioxidant agent.
 24. The rapidly solidified rareearth-transition metal-boron magnet material of claim 23, wherein thecoupling agent is an organotitanate coupling agent of the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup.
 25. The rapidly solidified rare earth-transition metal-boronmagnet material of claim 23, wherein the POSS additive istrisilanolphenyl or epoxycyclohexyl POSS.
 26. The rapidly solidifiedrare earth-transition metal-boron magnet material of claim 23, whereinthe antioxidant agent is a butylated reaction product of p-cresol anddicyclopentadiene antioxidant.
 27. The rapidly solidified rareearth-transition metal-boron magnet material of claim 23, wherein: theepoxy resin is epichlorohydrin/cresol novolac epoxy resin, theamine-based hardener is dicyandiamide hardener, the accelerator is anaromatic, tertiary amine accelerator, the lubricant is zinc stearatelubricant; and the organo clay additive is bis (hydroxyethyl) methyltallow alkyl ammonium salts with bentonite.
 28. The rapidly solidifiedrare earth-transition metal-boron magnet material of claim 23, wherein:said pre-coating is a trisilanolphenyl or epoxycyclohexyl POSS in anamount of about 0.1 weight percent to about 1 weight percent, by weightof the magnet powder; and said coating formulation consists essentiallyof, by total weight of the mixture, of about 0.54 weight percent toabout 2.75 weight percent of epichlorohydrin/cresol novolac epoxy resin,about 0.03 weight percent to about 0.17 weight percent of dicyandiamidehardener, about 0.01 weight percent to about 0.06 weight percent of anaromatic, tertiary amine accelerator, about 0.035 weight percent toabout 0.175 weight percent of zinc stearate lubricant, about 0.35 weightpercent to about 0.75 weight percent of an organotitanate coupling agentof the form(RO—)Ti(—OR′Y)₃ where R is a neopentyl(diallyl), Ti has a coordinationnumber of 4, R′ is a pyrophosphato segment, and Y is a dioctyl endgroup, about 0.003 weight percent to about 0.07 weight percent of anorganoclay comprising bis (hydroxyethyl) methyl tallow alkyl ammoniumsalts with bentonite, and about 0.003 weight percent to about 0.015weight percent of a butylated reaction product of p-cresol anddicyclopentadiene antioxidant.